<?php
/*define("aa","hello world",true);//定义常量（长量名，长量值，是否区分大小写，当为true时候输出常量的值不区分大小写，常量不需要$符号）
echo Aa."<br>";
//echo"<br>";
echo aa."<br>";

*/
$x=10;
$y=16;
echo($x+$y)."<br>";
echo($x*$y)."<br>";
echo($x-$y)."<br>";
echo($x/$y)."<br>";
$x+=50;
echo $x."<br>";
$x-=20;
echo $x."<br>";
$x %=7;
echo $x."<br>";
$y="hello";
$y.=" world";//连接字符串用.	串接	$txt1 = "Hello" $txt2 = $txt1 . " world!"  .=	串接赋值	$txt1 = "Hello" $txt1 .= " world!"
echo $y;
?>